A physically unclonable function (PUF) implemented in an electronic circuit can be used to securely store information even when the general layout of the PUF circuit is known. A PUF can be used to securely authenticate a compute device or to securely communicate with the compute device.
Magnetic tunnel junctions can be used to store data. In a magnetic tunnel junction, an insulator is sandwiched between a ferromagnetic fixed layer and a ferromagnetic free layer, and the orientation of a magnetization in a free layer relative to the orientation of a magnetization in a fixed layer is used to store a bit of data. The relative orientation of the magnetization of the free and fixed layers affects the resistance across the junction due to tunnel magnetoresistance, and so the orientation can be measured by measuring the resistance across the junction.